Compiler error: Method with Objective-C selector conflicts with previous declaration with the same Objective-C selector

by

I myself am also taking the Standford course and I got stuck here for a long time too, but after some searching, I found something from here: Xcode release notes and it mentioned something below:

Swift 1.2 is strict about checking type-based overloading of @objc
methods and initializers, something not supported by Objective-C.

// Has the Objective-C selector "performOperation:".
func performOperation(op: NSOperation) { /* do something */ }
// Also has the selector "performOperation:".
func performOperation(fn: () -> Void) {
    self.performOperation(NSBlockOperation(block: fn))
}

This code would work when invoked from Swift, but could easily crash
if invoked from Objective-C. To solve this problem, use a type that is
not supported by Objective-C to prevent the Swift compiler from
exposing the member to the Objective-C runtime:

  • If it makes sense, mark the member as private to disable inference of @objc.
  • Otherwise, use a dummy parameter with a default value, for
    example: _ nonobjc: () = (). (19826275)

Overrides of methods exposed
to Objective-C in private subclasses are not inferred to be @objc,
causing the Swift compiler to crash. Explicitly add the @objc
attribute to any such overriding methods. (19935352)

Symbols from SDKs are not available when using Open Quickly in a
project or workspace that uses Swift. (20349540)

what i did was just adding “private” in front of the override method like this:

    private func performOperation(operation: Double -> Double) {
    if operandStack.count >= 1 {
        displayValue = operation(operandStack.removeLast())
        enter()
    }
}

More Related Contents:

  1. Get letters from string swift
  2. How to lock orientation of one view controller to portrait mode only in Swift
  3. Wait until swift for loop with asynchronous network requests finishes executing
  4. Sending json array via Alamofire
  5. How do I print the type or class of a variable in Swift?
  6. How to get Ip address in swift
  7. What does “Protocol … can only be used as a generic constraint because it has Self or associated type requirements” mean?
  8. Dictionary wrong order – JSON
  9. CFRunLoop in Swift Command Line Program
  10. How to hash NSString with SHA1 in Swift?
  11. How to generate a random number in a range (10…20) using Swift [duplicate]
  12. How to apply the type to a NSFetchRequest instance?
  13. Understanding SpriteKit CollisionBitMask
  14. ARKit – What do the different columns in Transform Matrix represent?
  15. Printing a variable memory address in swift
  16. Main Thread Checker: UI API called on a background thread: -[UIApplication applicationState]
  17. Calling a Swift class factory method with leading dot notation?
  18. Can Swift return value from an async Void-returning block?
  19. USB Connection Delegate on Swift
  20. Check empty string in Swift?
  21. iOS13 Navigation bar large titles not covering status bar
  22. Multi-touch gesture in Sprite Kit
  23. Array element cannot be bridged to Objective-C
  24. Thread 1: EXC_BAD_INSTRUCTION when fetching data
  25. Swift: shortcut unwrapping of array of optionals
  26. Can I assign a default type to generic type T in Swift?
  27. iOS9 Swift File Creating NSFileManager.createDirectoryAtPath with NSURL
  28. How do I perform an auto-segue in Xcode 6 using Swift?
  29. Can Swift convert a class / struct data into dictionary?
  30. No Such Module ‘Parse’

Leave a Comment